Process and apparatus for forming structural members

ABSTRACT

A continuous cold forming process for making structural members from a strip of expandable material. Bends are formed along either edge of the strip and it is bent into a U or other shape having sides and a base. Slits are cut into the base in a manner which permits the formation of a web, and material adjacent to the slit is pushed out of the plane of the base. The base is subsequently pulled over convex or plain surfaces to promote expansion of the web. The web is deeply embossed or stretched and subsequently expanded by roller and fixed dies. A final embossing step completes the process. The apparatus includes a series of roller and fixed dies. The first series of stands form bends along the edges and bend the material into a U-shaped or other configuration. One set of roller dies have raised, tapered cutting edges which selectively cut the base in order to provide the basis for the formation of a web. Other roller dies pull the base over a convex surface and widen it. Roller dies with frustum-like pyramidal projections deform the web and subsequent roller and fixed dies stretch the web and flatten it.

United States Patent 1 Baxter [4 1 Jan. 21, 1975 PROCESS AND APPARATUS FOR FORMING STRUCTURAL MEMBERS [75] Inventor: Peter J. Baxter, Chagrin Falls, Ohio [73] Assignee: Modeo International Inc., Chagrin Falls, Ohio 22 Filed: May 3,1973

21 Appl. No.: 356,847

Primary ExaminerAndrew R. Juhasz Assistant Examiner-Leon Gilden Attorney, Agent, or Firm-Fay & Sharpe [57] ABSTRACT A continuous cold forming process for making structural members from a strip of expandable material. Bends are formed along either edge of the strip and it is bent into a U or other shape having sides and a base. Slits are cut into the base in a manner which permits the formation of a web, and material adjacent to the slit is pushed out of the plane of the base. The base is subsequently pulled over convex or plain surfaces to promote expansion of the web. The web is deeply embossed or stretched and subsequently expanded by roller and fixed dies. A final embossing step completes the process.

The apparatus includes a series of roller and fixed dies. The first series of stands form bends along the edges and bend the material into a U-shaped or other configuration. One set of roller dies have raised, tapered cutting edges which selectively cut the base in order to provide the basis for the formation of a web. Other roller dies pull the base over a convex surface and widen it. Roller dies with frustum-like pyramidal projections deform the web and subsequent roller and fixed dies stretch the web and flatten it.

10 Claims, 24 Drawing Figures PATENTED m2 I ms sum 1 or 3 PATENTEU JAN-2 1 1975 sum 20! 3 PROCESS AND APPARATUS FOR FORMING STRUCTURAL MEMBERS BACKGROUND OF THE INVENTION Metal structural members in buildings are becoming more popular as the supply of wood dwindles and its price increases. Accordingly, many different processes and machines have been proposed. One type of metal structural member is a solid channel. While having sufficient strength, the solid member has several deficiencies. It is relatively heavy and, therefore, expensive to transport and difficult to use on the site. It also has high thermal conductivity. As a result, both heat and cold are readily transmitted between the inner and outer walls.

A webbed structural channel alleviates the weight and heat transfer problems. Because of open spaces in the base, the member is naturally lighter and conducts significantly less heat. As a result, transportation and labor savings are realized andenvironmental benefits occur. That is, less insulation is required for a webbed structural member over a solid one for any given temperature differential.

Two basic types of webbed, metal structural members are the punched and expanded varieties. The punched members are generally made by bending a strip of material into the proper configuration'and then punching or otherwise removing sections of the metal in order to reduce the weight and form a web. This method provides a final product which is relatively light and strong but has the disadvantage of creating a significant amount of waste. The additional expense, because of the waste, makes this process less desirable.

Formation of structural members by selectively slitting part of the member and then pulling it apart to form a web eliminates the waste of the punched method. However, the stretching of the material during the formation of a web frequently causes cracks at points of stress. Watanabe U.S. Pat. No. 3,034,197 discloses one use of expandable metal in order to form structural members. In particular, the base of a U- shaped member is slit and expanded into a web through various steps. Substantial cracking of the web is experienced.

Terrell U.S. Pat. No. 3,298.081 discloses another continuous cold working process for forming an expanded metal structural member. Intermittent punching and roller dies are used with increasingly greater widths to expand the web. While the reduction of cracking is claimed, significant disadvantages in cost and efficiency are realized because of the intermittent nature of the process.

This invention provides a continuous cold working process which minimizes cracking and maximizes utilization of material and strength. In particular, this invention has found that incremental stretching such as embossing of the structural member produces significantly greater expansion capacity without cracking. Moreover, incremental stretching provides additional strength without increasing the weight of the material. Simultaneously slitting the material and deforming it out of its plane has also been found to increase its expansion capacity.

SUMMARY OF THE INVENTION A process of forming structural members includes supplying a strip of expandable material having a base,

Ill

slitting the base along its longitudinal axis and expanding it in order to permit formation of a web therein. The base is incrementally expanded in order to provide an increase in the expansion capacity of the web.

The apparatus includes a series of stands with roller and fixed dies and includes means for slitting the base of a strip of material in order to permit the formation of the web, a means for incrementally expanding the web in order to provide an increase in expansion capacity and a means for stretching the base transverse to its longitudinal axis in order to form the web. One type of means for incrementally expanding includes frustumlike projections on a pair of roller dies which deform the expandable material as it passes therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 1a are schematic representations of the apparatus of this invention.

FIG. lb is a cross-sectional view taken through section lblb of FIG. 1 and illustrates a cross-section of one of the stands.

FIGS. lc through 16 illustrate cross-sectional views lc-lc through l6l6 of the strip of material as it passes through the apparatus illustrated in FIGS. 1 and la.

FIG. 9a is a cross-sectional view taken through 9a-9a of FIG. la and illustrates slitting roller dies.

FIG. 13a is a section taken through l3a-I3a of FIG. 1 and illustrates the embossing dies.

FIG. 14a is a section taken through 14al4a of FIG. 1 and illustrates the roller dies for expanding the web.

FIG. 17 illustrates a completed section of the structural member of this invention.

FIG. 18 is a top view of the fixed die for expanding the web.

DETAILED DESCRIPTION OF THE DRAWINGS FIGS. 1 and la illustrate a schematic representation of the apparatus of this invention. It includes a series of mechanical stands 16 for cold working a strip of expandable material 22 which is uncoiled from a coil 24 which is rotatably mounted on an axis 26 held by a stand 28. The strip of material 22 is generally fiat as it comes off the coil 24 and may be any one of numerous sizes. The Applicant has used material which is about 2 inches wide and has a thickness of about 0.024 to in excess of 0.065 inches. The material that is utilized in this invention may be any one of numerous types but it should have the capacity to be expanded. The term expanded is used in the broad sense of being deformable so that it may be cold worked. Ferrous and nonferrous material have been found suitable for use in this invention.

The strip of material 22 passes through a set of guiding rollers 30 which are rotatably mounted on axes 32 and 34. As the material passes through the cold working stands 1 thru 8, the basic formation of a structural member takes place. As progressively illustrated in FIGS. 10 thru 8, the strip of material 22 has its outer edges bent back upon themselves in order to form bends 36 and 38. At stand 5, the material 22 is slightly bent along its length to form comers 40 and 42 to make sides 43 and 45 and a base 47. In subsequent stands 6 thru 8 and as illustrated in FIGS. 6 thru 8, the material 22 is worked until it is nearly U-shaped having bends along either longitudinal edge. Cold working stands I thru 8 and the process of cold working the material shown in FIG. thereof is generally standard and well known in the art.

The stands used in FIGS. 1 thru 8 are all similar and as shown in FIG. lb and generally have a roller die 44 with two rollers 46 and 48 having flanges 50 and 52, respectively. The roller 46 engages its complimentary roller 48 having sections 52 and 54 with flanges 56 and 58, respectively. As the material 22 passes between the roller dies, it has the flanges 36 and 38 formed thereon.

As illustrated in FIGS. 1a and 9 thru 17, additional stands 9 thru 16 continuously operate on and cold work the material 22. In actual use, the stands 8 and 9 are adjacent to but separate from one another. The material 22 passes between two roller dies in stand 9 as illustrated in FIG. 9a. Mating roller dies 60 and 62 cooperate to cut the base 47 of the material 22 as it passes therebetween. Cutting edges 66 and 67 rise out of the surface of the roller 60 and are tapered along one edge in order to push the material 22 out of the plane of the base 47 while it simultaneously cuts it. As particularly noted in FIG. 9, the severed material 68 is stretched out of the plane of the base 47 in order to provide a basis for the future formation of a web as the material 22 continues through this apparatus and process. As noted in FIG. 9a, the complimentary roller dies 60 and 62 are rotatably mounted on axes 70 and 73 and mounted on bases 72 and 74 in a conventional manner. It should be noted that various slitting patterns may be utilized. One of the simpler ways of slitting it is to make three rows of slits. The two slits nearest the corners 40 and 42 of the base are parallel to each other, have the same length and start at the same point along the length. The center slit would normally start at the center of the outside slits and continue to a point at the center of the next outside slits. It should be noted, however, that additional rows of slits and slitting patterns are possible in order to provide additional expansion of the web. In particular, five rows of slits could be utilized.

Stand 10, as noted in FIG. 10a, acts as the initial expansion means and includes complimentary roller dies 76 and 78. Roller die 78 has a convex surface 80 with flanges 82 and 88 at either side thereof which engage the sides 43 and 45 of the material 22. As the material 22 passes through the roller dies 76 and 78, the base 47 of the expandable material 22 is pulled or stretched over the convex surface 80. It has been found that the stretching of the web over a convex surface tends to expand it with a minimum of or no cracking, breaking, or splitting. Because the cold working of the metal is strenuous on it, cracking has previously been a common problem which normally occurs in the expansion step.

As the material 22 progresses, it passes through a fixed die 81 which is illustrated in FIG. 18 and includes a pair of diverging members 90 and 92 to engage the sides 43 and 45 of a structural member 51. As the base 47 enters under the members 90 and 92, the sides 43 and 45 engage the diverging members 90 and 92 and cause an expansion of the web. Rollers 94 aid in the passage of the material 22 therethrough. As seen in FIG. 1a, additional fixed dies 96, 98, 100 and 102 are located between the various stands and are also used to gradually increase the width of the structural member. It is anticipated, however, that the locations shown in FIG. 1a are not fixed and may be varied. It is important to note, however, that the primary expansion of the web is done with the roller dies and not with the fixed dies. Stands 11 and 12 again expand the webs by means of complimentary roller dies in which one of the rollers is convex and the other concave in order to stretch the web over the convex surface, thus, causing a gradual 5 expansion with a minimum of or no cracking.

One of the important steps in this invention and one of the more important parts of this apparatus are illustrated in FIGS. 13 and 13a which show the incremental expansion of the base 47. Incremental expansion is used in the sense that a relatively small area of metal is expanded for example by permanent deformation. A greatly increased expansion capacity is realized without the experience of cracking by incremental expansion. As shown in FIG. 13a, a pair of roller dies 104 and 108 work on the base 47 as it passes therebetween. The roller dies, as seen from the expanded view of a section thereof, include a series of frustum-like projections 110 having flat tops 111 and tapered sides 113. The frustum-like projections are offset from one another on the roller dies 104 and 108 and literally push into the expandable material and deform it. The base 47 becomes roughened as noted in FIG. 13. This incremental expansion which in some cases could be termed embossing literally creates additional material in the web which can be flattened and/or stretched in order to give an additional expansion capacity to the web.

Additional expansion occurs in stand 14 as the material is again passed between complimentary convex and concave roller dies. As illustrated at stand and in FIG. 15, the material is flattened to aid in utilizing the additional material from embossing and providing a finished product having a generally flat base. Flat rollers in stand 15 push the deformed material back into the plane of the base.

Stand 16 also has incremental expansion rollers similar but less severe than those illustrated in FIG. 13a. FIG. 16 shows the material as it passes through stand 16. The base 47 is once again embossed but to a slighter degree than occurs at stand 13. This final embossing step is used to give additional strength to the now completely expanded web. It should also be noted that stands 15 and 16 could be reversed and that the embossing step which occurs in FIG. 16 is not absolutely necessary. It should also be realized in this invention that the various expansion steps with the roller dies and the fixed dies could be modified. The important section of this invention is the incremental expansion of the web with the subsequent expansion thereof. The simultaneous slitting and expansion of the material adjacent to the slits also provide an important part of this invention.

The final product as shown in FIG. 17 is an expanded base 47 forming a web 65 having sides 43 and 45 with bends 36 and 38, respectively. Although this invention is described with respect to the formation of a substantially U-shaped member, it should be understood that it would be relatively simple to form L-shaped, I- shaped or other similar structural members.

The invention has been described in great detail sufficient to enable one of ordinary skill in the art to make and use the same. Obviously, modifications and alternations of the preferred embodiment will occur to others upon a reading and understanding of the specification and it is out intention to include all such modifications and alterations as part of our invention insofar as they come within the scope of the appended claims.

I claim:

1. An apparatus for forming structural members from strips of expandable material having a longitudinal axis comprising:

means for slitting the base in order to permit formation of a web in the base;

means for incrementally expanding the web in order to provide an increase in expansion capacity of the web without tearing, said means for incrementally expanding including frustum-like projections which engage and deform small areas out of the plane of the base;

means for stretching the base transverse to the longitudinal axis in order to form a web and utilize the deformed areas for expansion of the base.

2. The machine of claim 1 wherein the means for slitting the base also includes a means for pushing the material adjacent to the slits out of the plane of the base.

3. The machine of claim 2 wherein the means for slitting and pushing are complimentary roller dies, one of the roller dies having upwardly protruding tapered cutting edges.

4. The machine of claim 3 wherein the means for incrementally expanding comprises complimentary roller dies having frustum-like projections extending therefrom.

5. The machine of claim 4 wherein the frustum-like projections on one roller die are offset from the frustum-like projections on the other roller die in order to deform the expandable material therebetween.

6. The machine of claim 4 which further includes a means for expanding the base positioned between the means for cutting and the means for incrementally expanding, and a means for embossing the web positioned to operate on the material after it has been incrementally expanded and stretched in order to add strength to the web.

7. The machine of claim 6 wherein the means for stretching and the means for expanding each include a pair of roller dies, one of the roller dies in each pair having a convex surface and the other roller die in each pair having a concave surface so that the material pulled over the convex surface in order to expand the web with a minimum of cracking.

8. The machine of claim 7 which further includes means for flattening the web in the base after it has been incrementally expanded and stretched by the means for stretching.

9. The machine of claim 8 which further includes fixed dies which engage the material and cause the expansion of the web.

10. The machine of claim 9 which further includes a means for forming a bend along either edge of the sides. 

1. An apparatus for forming structural members from strips of expandable material having a longitudinal axis comprising: means for slitting the base in order to permit formation of a web in the base; means for incrementally expanding the web in order to provide an increase in expansion capacity of the web without tearing, said means for incrementally expanding including frustum-like projections which engage and deform small areas out of the plane of the base; means for stretching the base transverse to the longitudinal axis in order to form a web and utilize the deformed areas for expansion of the base.
 2. The machine of claim 1 wherein the means for slitting the base also includes a means for pushing the material adjacent to the slits out of the plane of the base.
 3. The machine of claim 2 wherein the means for slitting and pushing are complimentary roller dies, one of the roller dies having upwardly protruding tapered cutting edges.
 4. The machine of claim 3 wherein the means for incrementally expanding comprises complimentary roller dies having frustum-like projections extending therefrom.
 5. The machine of claim 4 wherein the frustum-like projections on one roller die are offset from the frustum-like projections on the other roller die in order to deform the expandable material therebetween.
 6. The machine of claim 4 which further includes a means for expanding the base positioned between the means for cutting and the means for incrementally expanding, and a means for embossing the web positioned to operate on the material after it has been incrementally expanded and stretched in order to add strength to the web.
 7. The machine of claim 6 wherein the means for stretching and the means for expanding each include a pair of roller dies, one of the roller dies in each pair having a convex surface and the other roller die in each pair having a concave surface so that the material pulled over the convex surface in order to expand the web with a minimum of cracking.
 8. The machine of claim 7 which further includes means for flattening the web in the base after it has been incrementally expanded and stretched by the means for stretching.
 9. The machine of claim 8 which further includes fixed dies which engage the material and cause the expansion of the web.
 10. The machine of claim 9 which further includes a means for forming a bend along either edge of the sides. 